1. Field of the Invention
A method for displaying the vehicle safety distance and, more particularly, to a method for displaying the vehicle safety distance with predictive display and lane departure warning functions, to thereby warn the driver of the lane departure situation timely, to ensure traffic safety.
2. Brief Description of the Related Art
For the vehicle equipments, safety is most important. In recent years, image recognition and wireless detection technology become more sophisticated, a lot of technology is applied on vehicle safety, such as the functions of suggesting safety distance to the front car and lane departure warning in response to market demand.
Currently, there are two kinds of lane departure warning systems. In one of the two systems, a photoreceptor is set on the location near the two front wheels under the car. When the photoreceptor senses the ground color near the wheels changed, the displayed color of the display unit may change to white or yellow from black, and the system determines that the car departures the lane. The cost of the method is low, but malfunction may be occurred easily. In another system, a camera lens is installed in front of the car, usually in a high place inside the windshield for capturing the image in front of the car, which includes the lane line. An image recognition method is used to extract the lane line in the image and determine the shift amount of the lane line. When the lane line is shifted to the predetermined location, the system determines as lane departure. The cost of the method is high, but the probability of malfunction is low.
There are also two kinds of vehicle safety distance warning systems. In one of the two systems, a millimeter-wave radar (30 GHz˜300 GHz) with high frequency or a laser radar is used to perform the determination of the vehicle safety distance, the weathering resistance and the distance performance distance are both excellent, but the cost is high, and the system cannot identify whether the car is in the same lane or in the roadside fence, thus malfunction may be occurred easily. In another system using an image recognition method, the forward object is shot by an image camera lens with fixed angle. The extraction of the forward object is converted into the distance by the elevation angle of the image relative to the image lens. The cost is low, and the same camera lens may be shared with the lane departure warning system to thereby share the cost, but the weathering resistance is bad, and its determination for the front car may be affected by the reasons, such as night, fog, heavy rain.
The above vehicle safety distance warning systems using radar wave are usually installed in the high-priced cars, some of the systems are further connected to the actuator system to start the brakes for assisting brake when necessary. Since the cost of the vehicle safety distance warning systems is high and a lot of components are involved in, it cannot be installed in the common price cars, and it is more difficult for the car owners to install the system by themselves after buying the car.
In the commercially available vehicle safety distance warning systems, the high-end products may drive the brake and the actuator system of the car after determining the front vehicle distance, and may automatically adjust the car speed according to the front vehicle distance to keep an appropriate distance from the front vehicle. Some low-end products may mark the front vehicle distance on the screen after determining it, but the drivers do not have intuitive feelings about this kind of vehicle distance data, thus it is not helpful to the drivers. Another kind of the low-end products warn the driver by images or sounds when the front vehicle distance is too short, the drivers cannot receive enough information to keep the vehicle safety distance before being warned.
If the traditional lane departure warning device does not detect the lane, it does not warn to drivers even when the car has already departed the lane. Similarly, if the vehicle safety distance warning device cannot detect the front car, it does not warn to drivers even when the front vehicle distance is too short. If encounter these situations, instead of improving traffic, this kind of safety devices may let drivers feel safe and not pay attention on the road.
In order to solve the drawbacks of the above vehicle safety systems and warning devices, the industry disclose various related technology continuously, such as the patent reference, such as the patent reference with TW publication no. 200951892 (hereafter called the cited reference), which is a typical representative (as FIG. 1). The portable electronic device 11 of the cited reference is consisted of a camera lens 12, a speaker 13, a computing unit 14, a display unit 15 and a vibration unit 16. The speaker 13 is set on the portable electronic device 11; the camera lens 12 is set on the portable electronic device 11 for capturing a real-time road image 121; the display unit 15 is set on the portable electronic device 11 for displaying the above real-time road image 121. The computing unit 14 is set inside the portable electronic device 11, which includes an image analysis software 141, which judges whether the vehicle is located in the lane according to the traffic markings in the real-time road image 121, the speaker 13 sends out a warning signal 131 to remind the driver that the vehicle is departed the lane if the vehicle is not located inside the lane. If the portable electronic device 11 is set to silent mode, the driver may be reminded that the vehicle is departed the lane by the vibration of the vibration unit 16. The driver may further use the API system to turn on the camera lens 12 to shot the real-time road message, also may open the camera function originally set by the portable electronic device 11 directly to obtain the real-time road image 121, and the shot image may be transmitting to the display unit 15 for displaying by instant transmission technology.
The steps of the operation method of the cited reference (as shown in FIG. 2), the portable electronic device 11 is started to a driving safety mode, in the step 21, a camera lens 12 is used to get the real-time road image 121 actually; and then in the step 22, the real-time road image 121 is sent to the computing unit 14 and displayed on the display unit 15; and then in the step 23, the computing unit 14 is used to analyze the real-time road image 121 by using an image analysis software 141. In step 24, judging whether the vehicle is departed the lane according to the location of the lane on the road in the real-time road image 121. For example, judging whether there is only one or a little part of the strip whose color similar to the two lane lines on the real-time road image 121, if yes, the computing unit 14 judges that the vehicle has already departed the lane; if there are two strips whose color similar to the lane lines on the real-time road image 121, the computing unit 14 judges that the vehicle is in a safe driving condition. If the computing unit 14 judges that the vehicle departs the lane, in step 25, the portable electronic device 11 make a sound to remind the driver that the vehicle maybe departs the lane. If not, repeat executing step 21.
Although the cited reference solved the drawbacks of the traditional vehicle safety systems, the real-time road image 121 shot by the camera lens 12 is a virtual image, which is not as clear as marked lines in visual appearance to impressive the driver. The driver may not easily be aware of the impending driving danger from the images in advance before the vibration or the warning sound starts.